A visa is essential for entering Cambodia and it can be obtained from the Cambodian Embassy in your country. Exemption is given from providing proofs of return tickets. And it takes three days to obtain visa from the date of application if dropped off and picked in person. Whereas it takes seven to ten days if a courier service is used.
Electronic visas can also be issued. Express visas are issued within 24 hours! A visa is valid up to one month from its issuance date. However an extension can be made from the Immigration Office in Phnom Penh for up to one month in tourist visas and 12 months in business visas.